Which statement about the changes in the history of life on earth is correct? a. the theory of plate tectonics explains why the early oceans contained more iron than the oceans contain today. b. the first photosynthetic organisms probably caused worldwide extinctions because they put large amounts of dust into the air. c. geological forces and living organisms have shaped the physical features of the planet. d. the fossil record shows that global temperature changes of only a few degrees have not had much of an impact on living things.

Explain how the political influence of african americans leaders became weaker.

The carbon cycle is best defined as a process in which a. carbon changes from inorganic forms to organic forms and back b. carbon is changed into other elements such as oxygen or nitrogen c. carbon is continually created from the sun’s energy by plants d. carbon is consumed and regenerated from other elements such as oxygen and nitrogen

Which of these is true of the cytoplasm of an unfertilized egg? a. it is an unevenly distributed mixture of mrna, proteins, organelles, and other substances. b. it does not contain substances that are important in directing development. c. these substances are supplied by the sperm. d. it does not contain substances that are important in directing development. e. development is directed solely by the surrounding cells. f. it is a homogeneous mixture of mrna, proteins, organelles, and other substances. g. it does not contain substances that are important in directing development. h. these substances are produced by the dna of the fertilized zygote.